 Anton van Leeuwenhoek (1600’s)-first to spot the living organisms in pond water using an early microscope  Robert Hooke-(1665) viewed thin layers of plant cells under microscope, coined the term “cells”  Cell Theory  All living things are composed of cells  Cells are basic units of structure and function in living things  New cells come from previously existing cells

 Cells range in size from 5 micrometers (bacteria) to 1000 micrometers (amoeba - Chaos chaos)  All cells have:  Cell membrane: thin, flexible barrier around the cell  Some cells have a cell wall surrounding the cell membrane (plant cells)  Nucleus: contains genetic material and controls cell activity  Cytoplasm: material inside cell membrane excluding the nucleus

 Prokaryotes: cells with cytoplasm and cell membranes but NO nucleus  Prokaryote example: bacteria  Eukaryotes: cells with nuclei and organelles  Eukaryotes can be single celled organisms or part of a larger organism

 Cell walls: found in plants, algae, fungi, and most prokaryotes, but not in animal cells  Cell wall provides support and protection for the cell  Cell wall made from carbohydrate and protein  Plant cell walls are composed mostly of cellulose

 Nucleus contains the genetic information of a cell (DNA) and controls most cell processes  Chromatin: granular material visible inside a cell  Chromatin condenses during cell division to form chromosomes (contains genetic information)

 Nucleolus-small, dense are within the nucleus which ribosomes are assembled.  Ribosomes aid in intracellular protein production  Nuclear Envelope-surrounds the nucleus, allows some material to move in and out of nucleus (RNA)

 Cytoskeleton is a network of protein filaments that helps maintain the shape of the cell.  Cytoskeleton also aids in cell movement  Microtubules assist in cell division, helping chromosomes to separate  Microtubules also may form cilia and filaments

 Microfilaments are long, thin fibers that function in cell movement and support  The cytoskeleton also helps in moving organelles within the cell

 Ribosomes-proteins are assembled in the ribosomes  Endoplasmic reticulum-components of the cell membrane are assembled and some protein modification occurs  Golgi apparatus-enzymes attach carbohydrates and lipids to proteins  Lysosomes-contain enzymes which help breaking down lipids, carbohydrates, and proteins into a usable form for the cell  Lysosomes also help break down organelles that are no longer useful to the cell

 Sac-like structures that serve as storage structures within a cell  Water, salts, proteins, & carbohydrates may require storage  Pressure within plant vacuoles provide some structural support to help hold up leaves & flowers  Vesicles are smaller vacuoles sometimes involved in transport

 Chloroplasts contain chlorophyll, which can convert sunlight into energy rich molecules  Chloroplasts are Natures original solar cells  Only green plants and some algae contain chlorophyll.

 Release energy from food molecules  Specifically, mitochondria use energy from food to make high energy compounds that a cell can use for growth, development, and movement  Mitochondria are found in almost all eukaryotic cells

Chloroplasts and mitochondria contain some of their own genetic information (DNA) This DNA controls the function of the cell

The cell functions in much the same way that a factory does. Walls & roof-cytoskeleton Transportation within the factory-cytoskeleton Main office-nucleus sends out instructions (RNA) Ribosomes-factory machine turning out Customizing shop/shipping-Golgi Apparatus Power plant-mitochondria/chloroplasts

The cell membrane controls what goes in/out of the cell and provides protection and support.

Diffusion is movement of a substance to move through/across a cell membrane. It does NOT require energy to do this. Material will move from a higher concentration to a lower concentration, with goal being equilibrium of the concentration. Concentration is the amount of solute in a given amount of solvent, thus making a solution of a particular concentration

Permeable-a membrane that allows a substance to cross it is “permeable” to that substance Impermeable-A membrane that DOES NOT allow substances to cross it is “impermeable” Osmosis is the diffusion of water through a selectively permeable membrane Osmosis will occur across a membrane until an “isotonic” condition is reached. (Isotonic literally means “ equal strength” Hypertonic- Hypotonic-

Osmosis exerts a pressure (osmotic pressure) on the hypertonic side of a selectively permeable membrane Cells (containing salts, sugars, proteins, etc will be hypertonic to fresh water, thus there will be a net movement of water into a cell. This will cause a cell to swell up, potentially bursting. Why does this not usually happen? Because cells body cells are rarely if ever surrounded by pure water. What about cells such as bacteria and plant cells that may be surrounded by fresh water? Why don’t they burst? Because they have a tough cell wall which restricts expansion.

Facilitated diffusion is when a specific protein assists a particular molecule to move across a membrane from a hypertonic to hypotonic situation Example: RBC (red blood cells) use a specific protein to allow glucose to pass through the membrane

A movement of materials across a membrane from lower to higher concentration (swimming upstream!) Active transport acts like a pump, thus it requires energy. Endocytosis-process of taking materials into a cells by infoldings or pockets of the cell membrane

Phagocytosis-large particles taken into a cell by endocystosis Exocytosis-removal of large amounts of material from a cell

Unicellular Organisms may be- -eukaryotic or prokaryotic --live as individual cells or in a colony A colony is a group of individual cells that live together but have some specialized structures and specialized functions Multicellular organisms have specialized cells that that perform particular functions within the organism Human body has many examples of specialized cells that do a particular job for the body to live (RBC, WBC, pancreatic cells, etc

Cells combine to form- Tissues, which combine to make- Organs, which work together to make- Organ systems

Cells-division of labor among cells of multicellular organisms Tissues-organized, specialized cells working together 4 types of tissue in most organisms muscle epithelial (skin) nervous connective (bone, blood, cartilage, lymph)

Tissues working together for a common cause in an organism is an organ Organ system is a group of organs that work together Human body contains 11 major organ systems including- Muscular Skeletal Circulatory Nervous And many more!